From some other command line output that you posted it seemed to me that the (standard?) USB audio device driver from Alsa was loaded. It almost looks like the Presonos Studio 1810 is not supported by this driver. Almost every cheap USB sound "stick" up to my Behringer 404HD works with the driver called snd_usb_audio.

Check if the kernel module (read: driver) named snd_usb_audio is loaded:

Wat seems very strange to me is that they say that the device works in MacOS because it's class compliant. The Presonus Studio1810c looks like a very nice audio card to me. Pity that it doesn't seem to work in Linux. I couldn't find anything on the internet about this device and Linux, other than that Linuxers ask for a port to Linux of Presonos' software. Is it a very new device?

If it is really class compliant then the developers at Alsa might pick up on it and find a way to support it. The tip you got from somebody to contact ALsa might be your best option at the moment...

Linuxmusician01 wrote:
Check if the kernel module (read: driver) named snd_usb_audio is loaded:

Both snd_usb_audio and snd_usbmidi_lib modules are loaded upon connecting S1810c. I can check module parameters in /sys/module/ ..., I also changed index parameter by editing /etc/modprobe.d/alsa-base.conf and it worked as expected.

Linuxmusician01 wrote:
Wat seems very strange to me is that they say that the device works in MacOS because it's class compliant.

I just checked it on a Mac. Disconnected network to make sure nothing is downloaded and connected the device, for the first time on this computer. The device showed up in System preferences but I couldn't use it from there because it said "The selected device has no input / output controls", probably to be expected. Opened (pre-installed) Audacity, both play and record worked immediately. That's even without the software that Presonus recommends (was not installed). So it looks like it is class compliant.

Linuxmusician01 wrote:
If it is really class compliant then the developers at Alsa might pick up on it and find a way to support it. The tip you got from somebody to contact ALsa might be your best option at the moment...

Thanks for the tip, I agree, hopefully I have enough info by now to convince ALSA devs to look at this

For people who might be interested in Presonus 1810c, there is a patch now, thanks to Nick Kossifidis and Takashi Iwai (alsa-devs). It's disappointing that Presonus people didn't supply the info needed to develop the patch, it seems it would've been very easy for them.

I used the patch to recompile usb_snd_audio for kernel 5.3.0. The only thing I had to do in addition to the standard procedure for building a kernel module was to merge few lines that were added to mixer.h after 5.3.0. I didn't check midi, otherwise works perfectly.